Researchers at Rush University created a technology that delays the release of less nutritious snacks in vending machines. The machines -- which tracked over 32,000 purchases -- alerted users which items would be delayed by 25 seconds, and which would release immediately.

The delay helped increase healthy selections by 2 to 5 percent without hurting the overall sales revenue from the machine.

Healthy snack purchases also increased when the items were discounted by 25 cents.